ehcoplex 

Replacing the cracked pulleys on a Suntour Cyclone MK-II. Discovered that, of course, the minuscule tab that goes into the split bolt for the top pulley is missing...
Comparing to the rebuild photos from another thread, it seems a bushing/washer may also be missing from mine- where does the circled piece below go (this is the bit I don't seem to have...)?



And then there's this part- on my Cyclone this bushing doesn't have the little 'hook' in it- is this another bit that's missing? *There is a big plastic bushing here, just it's completely round and doesn't have this extra hook bit.




I only very briefly test rode the bike this RD was on when I bought it months ago, and it shifted OK. But in dismantling the mech right now the top pivot/pulley bolt was quite loose. Test fitting it back together (without the missing little tab- I'll have to grind something to put in there....), if that pivot/pulley nut is tightened, the cage binds and won't pivot. Does having the tab in there remedy this, or is there a bushing part that's missing and that's the problem?

(I did search for an exploded diagram of a Cyclone MK-II RD, but haven't found one.....)

steelbikeguy

the item that you circled is just the nut that goes on the lower pivot shaft.
It's just positioned so that the side that you usually see is facing down in the photo.

here's a shot of the assembled derailleur, just for the benefit of those not familiar with the derailleur...




The hook portion of that bushing just fits into the matching portion of the derailleur body, as seen in the photo below.
This seals up the chamber where the spring is located.



The bushing sounds like it might be too thick?? If it doesn't have the same shape as the one in my photos, it might not be the correct part.


Steve in Peoria

ehcoplex 

steelbikeguy , Doh, of course the first bit is the nut for the pivot!

I wonder if maybe there were some slight design mods over the Cyclone MKII run and they didn't all have the extra 'hook' part to seal the spring.. Looking closer at mine it doesn't seem like another bushing could fit in the assembly. I'm wondering if maybe with the little tab in the slot the pivot nut will get tight without causing the pivot to bind.... Time to fire up the dremel and make a tab out of... something....

steelbikeguy

I've been surprised at the minor variations in the first generation Cyclone derailleurs. I'm not well versed in the Mk II, so it seems possible that they could have tweaked the design here and there. I suppose the important thing is whether the bushing still mates up nicely with the body?

There's a chance that someone has grabbed a bushing from another derailleur and it might not be compatible with yours. Did it bind before you took it apart?

Steve in Peoria

Aardwolf

You've probably seen it but here's the diagram:




I replaced the pulleys on mine a while back: used BBB RollerBoys sealed bearing pulleys, they work really well
https://www.bikeforums.net/classic-v...-bdp-01-a.html

ehcoplex 

I hadn't seen that diagram- my searches kept coming up with 1st gen diagrams. Interesting that the bushing with the extra 'hook' bit to seal the pivot spring isn't labelled as a separate part in the diagram...

The pivot didn't bind up before I took it all apart, but I rode the bike it came on very little, and the pivot nut was pretty loose...

Aardwolf

The diagram is from Disraeli Gears website: https://www.disraeligears.co.uk/site/home.html

In particular the 1983 SunTour small parts catalogue: https://www.disraeligears.co.uk/site...og_-_1983.html

Prowler 

I have a MKII on my Fuji TS III which works beautifully. It did not come to me with the “spring retainer” - part 18 in the above diagram. I could not figure out what it was for, as if the center tab of the spring will climb up out of the slot in the pivot shaft and sneak out through the hole in the tension nut - part 15. After I cleaned and reassembled the derailleur, I closed the hole in the tension nut with a rubber plug, to keep dirt out of the RD, then put it all to work. I still wonder how important that part 18 retainer is. Open to suggestions.

ehcoplex 

My understanding is that the 'spring retainer' is, at least partially, to keep the slotted end of the bolt from squeezing together when the nut get's tightened down (causing the nut to slip/strip/etc). Hard to see how the spring needs 'retaining'...

ehcoplex 

For posterity/completeness sake, here's the parts diagram of the specific Cyclone in question (the earlier parts scan was for medium or short-cage...

ehcoplex 

In perusing the parts catalogs on Disraeli, the only thing I can find with a spring bushing that doesn't have the little hook bit is the Superbe Pro. Interestingly, it looks like that RD has the same spring setup, just doesn't have the hook bit to 'seal' it.

ehcoplex 

But while we're on it...... does anyone know for certain what the purpose of that little tab actually is? Yeah, it says 'spring retainer tab', but it's really hard to see how it actually retains the spring!

*unless maybe the shape of it, with the tiny, tiny little 'wings' at the bottom allows the nut to tighten down without binding the pivot action......

steelbikeguy

I was rather shocked when the parts list didn't identify #17 as "weird doo-hickey".

It does seem like the nut should be adequate to keep the spring in place, I won't rule out that the end of the spring might creep towards the end of that shaft and cause some odd problem with the spring.
After spending a career in engineering, I've seen various cases where fixes were made to prevent a weird thing from happening. It's made me reluctant to just look at a design and say "I don't know why that part is there, so I'll just remove it". At the same time, I've seen people using a design that didn't understand it, and totally fail to adjust values of some parts to suit how they were using it.
In summary, don't bet against the designer's choice, especially when it's been validated by being in production for years.

It is good to see the exploded parts diagram, just to clearly indicate how that part should be oriented.

Steve in Peoria

ehcoplex 

Point(s) all taken- though I assume that part is now unobtanium on its own, and I’m not sure I’ve got the micro-dremel skills to fashion one…. I wonder if a bit of locktite would hold the pivot nut at tight-but-not-binding..

steelbikeguy

I would suggest picking up a really beat up Cyclone Mk II on ebay and getting the part from it. I've done this to get the lower pivot spring for the first generation Cyclone. Or practice with the dremel??

I'm not sure what sets the proper spacing of the nut. My guess is that it is the shim, which seems to be SunTour's solution to a lot of these sorts of problems. The downside is that a previous owner may have lost or damaged the proper shims, and now you've got to try to improvise. Might be another reason to buy a beat-up derailleur for parts.

Steve in Peoria
(more than a few Cyclones in the parts box)

ehcoplex 

[QUOTE=steelbikeguy;22656525]I would suggest picking up a really beat up Cyclone Mk II on ebay and getting the part from it. [/QUOTE

Though I wonder what the odds of a beat-up RD from eBay actually still having that minuscule bit are!

steelbikeguy

[QUOTE=ehcoplex;22656571]I suspect that you should be able to tell from the photos whether or not the piece is there.
In my photos below, it seems easily discernible.





Steve in Peoria

ehcoplex 

[QUOTE=steelbikeguy;22656611]In theory, yeah, but a perusal of the offerings on eBay indicates it's really difficult to tell in most photos (or most of them are actually missing the tab!)..

ehcoplex 

Tightening the pivot nut didn't cause the cage pivot to bind? If you were able to tighten up the nut and the cage still moved as it should indicates that the tab doesn't have anything to do with how the nut tightens down and that my pivoting issue when I tighten the nut is from something else....